Abstract:
Glass-ceramics glaze based on the CaO–MgO–Al2O3–SiO2 (CMAS) system was obtained by controlled crystallization of glass prepared from Egyptian raw materials. The glass-ceramics compositions were designed to crystallize leucite and wollastonite and so gradual additions of K2O were added to crystallize leucite in different amounts. The influence of adding Cr2O3, MnO2, CaF2 and Cs2O as nucleating agents on the sequence of crystallization, microstructure and microhardness were studied. Powder samples were pressed and heat-treated at different temperatures according to DTA results. Another heat treatment at 1100 °C for 3 h was carried out to study the effect of increasing temperature on the developed phases. Microhardness was
measured for the different glass-ceramics produced. XRD and SEM were used to study the crystallized phases and microstructures. Leucite (KAlSi2O6) and wollastonite (CaSiO3) were detected. The amount of leucite was increased by increasing its percentage in samples.The microstructure was changed depending on the composition, the nucleating agent added and the heat-treatment parameters. The microhardness of the prepared glass-ceramics reached 890 HV.